In the process of a printer printing, it often happens that the print process is interrupted due to a paper jam at the start of printing, or a blank page is output because the printer has run out of ink. In such cases, it may be difficult for an operator to determine the cause of the problem simply by looking at the printer. Typically, the printer is equipped with a flashing LED or sounding buzzer indicating the occurrence of a paper jam, a lack of ink or some other error, in order to alert the operator of the cause of the problem. However, unless the operator either memorizes all the error patterns or refers constantly to the user's manual, the operator will be unable to understand what type of status error has occurred. In addition, as printers have become more powerful and sophisticated the types of statuses that must be monitored and the types of errors that must be detected have also increased, making it difficult to express all these different statuses by a simple pattern.
In order to cope with such a situation, a status monitor has been developed that uses two-way communication between the printer and the computer to update the operator graphically and in real time on the status of the printer.
There are a variety of ways of displaying the status of the printer on such status monitors. For example, the status monitor may itself communicate directly with the printer and display a status of the printer according to the information sent back from the printer. Or, with Microsoft's Windows® OS, it is possible to ascertain completion of a print job or the occurrence of an error in the printing apparatus through communication with a printing apparatus connected to the computer by IEEE 1284- or USB 1.1-compatible two-way communication established through execution of a process called language monitor, in a spool system that outputs print data from a spool, via this language monitor. The status monitor can obtain the information sent back from the printer via this language monitor and the status can be displayed.
However, in either case the statuses that the status monitor can display are limited by the information sent back from the printer.
Microsoft's Windows® is equipped with a function called a print processor for processing a data stream of print data. This print processor only performs certain processes, such as saving a data stream of print data created by a kernel module that graphically processes output such as display and printing like a GDI (Graphics Device Interface) or a printer driver to a storage medium and outputting the saved data stream of print data to a system (the GDI) or printing apparatus. The print processor can be equipped with a function that stops the data stream or that stops the data stream due to a query from the operator. In the event that a data stream of print data is stopped by this type of function provided in a print processor, the status monitor cannot obtain information on the status of the printer and accordingly also cannot display such status information.
In recent years, it has become possible to build a network printer system by connecting a plurality of client computers and print servers (server computers) and a printer via a network. In such a network printer system as well, for any given print job from a client, if for some reason the print processor of the print server stops the data stream as described above, other operators are unable to print out from the client computer. Yet this condition is not status information sent back from the printer, so the above-described status monitor of the client cannot notify the operator of this state.
Thus, as described above, when the cause for a print interruption lies not with the printer but the computer, there is no way for the operator to know the reason for the stoppage.